👉 The Jeffrey fluid, also known as Jeffrey's fluid or Jeffrey's serum, is a fictional substance from the popular science fiction television series "Star Trek: The Next Generation." Introduced in Season 2, Episode 21, it is a mysterious, highly advanced biological fluid created by the enigmatic and powerful Captain Jean-Luc "Jeffrey" Krelin, a member of the Krelin family with extraordinary genetic abilities. The fluid is believed to enhance human capabilities, granting its users heightened intelligence, physical strength, and other extraordinary traits. Its exact composition remains unknown, adding to the series' intrigue and serving as a plot device to explore themes of power, ethics, and the nature of humanity.